1. Field of the Invention
The present invention relates to a board connecting component (hereinafter, referred to as “board connector”) that connects a plurality of boards mounting electronic parts such as semiconductor devices (hereinafter, referred to as “IC”) and chip parts, and to a three-dimensional connecting structure using the board connector.
2. Background Art
Conventionally, a board connector for connecting between boards such as module boards mounting electronic parts such as ICs and chip parts uses a multi-contact connector composed of plug and socket parts, or a pin connector with a plurality of contact pins fixed through a resin spacer.
FIG. 10 is a sectional view showing a makeup in which two pieces of module boards 110 and 120 are connected by means of conventional pin connector 100. Pin connector 100 is composed of resin spacer 102; and a plurality of metal contact pins 104 fixed through this resin spacer 102. Meanwhile, module board 110 is formed with circuit pattern 114 on one surface of wiring board 112, and a given position of the circuit pattern 114 mounts electronic parts 116 such as chip parts and ICs thereon. In the same way, the other module board 120 is formed with circuit pattern 124 on one surface of wiring board 122, and a given position of the circuit pattern 124 mounts electronic parts 126 such as chip parts and ICs thereon.
Connection between module boards 110 and 120 using pin connector 100 is made as follows: That is, first position metal contact pin 104 of pin connector 100, with respective circuit patterns 114 and 124 of module boards 110 and 120. Next have the top and bottom ends of metal contact pin 104 penetrate respective circuit patterns 114 and 124. Then, join circuit pattern 114 and the bottom end of contact pin 104 together; and circuit pattern 124 and the top end of contact pin 104, respectively, at soldering joint 128 with solder. This completes connection between module boards 110 and 120 using pin connector 100.
Meanwhile, with reduction in size and weight and with higher functionality, of mobile devices and the like, the number of contact terminals between module boards tends to increase. Accordingly, a connector as a board connector needs to be smaller in area per one contact terminal, and thus the effort is being made to reduce the pitch of contact terminals of a pin connector.
However, in the connection method by a pin connector, a large stress is added to the joint of a pin connector with the difference in fluctuation in size due to temperature change between members composing the joint, or with an external impact force. Accordingly, a structure for absorbing such a stress is being studied.
Japanese Patent Unexamined Publication No. H06-310195, for example, shows the following connecting structure. That is, as a result that module boards 110 and 120 are connected together as shown in FIG. 12, using pin connector 130 as shown in FIGS. 11A and 11B, a stress due to thermal expansion of resin spacer 132 and others is absorbed. FIG. 11A is a plan view of the structure, and FIG. 11B is a sectional view of the structure as has been cut in a longitudinal direction. FIG. 12 is a sectional view showing a state in which module boards 110 and 120 are connected together using this pin connector 130.
A plurality of metal contact pins 134 vertically penetrating are insert molded and fixed to resin spacer 132 of this pin connector 130. Further, as shown in FIG. 11B, both the right and left ends of the bottom surface of pin connector 130 have flexible elastic piece 136 projecting obliquely downward.
As shown in FIG. 12, two pieces of module boards 110 and 120 are connected using this pin connector 130. The concrete procedure is as follows: That is, first have the top and bottom ends of metal contact pin 134 penetrate circuit patterns 114 and 124, respectively. Then, join the top end of contact pin 134 and circuit pattern 124; and the bottom end of contact pin 134 and circuit pattern 114, respectively, at soldering part 128 with solder. In this case, downside module board 110 is fixed so as to touch flexible elastic piece 136 on the bottom surface of resin spacer 132.
This makeup allows, even if resin spacer 132 of pin connector 130, and module boards 110 and 120 thermally expand due to heat generated by electronic parts 116 and 126 mounted on module boards 110 and 120, or the change in the ambient temperature, a stress generated thereby to be absorbed by flexible elastic piece 136. As a result, a stress is not added to soldering part 128 even if board connector 130 is heated by electronic parts 116 and 126 or the high ambient temperature, retaining a stable soldering condition. Here, flexible elastic piece 136 may be provided on the top surface of resin spacer 132, in addition to the bottom surface.
However, mobile devices have significantly higher functionality in recent years, further increasing the number of terminals of a connector, and strong devices against a drop impact and the like have been demanded as well. To cope with this matter, in the connecting structure with the above-mentioned pin connector, through-holes are provided on the module board, which is connected to the circuit pattern by having contact pins penetrate the through-holes, and a flexible elastic piece absorbs a heat stress as well. However, such a structure, although a thermal stress can be absorbed, disables circuit patterns or electronic parts to be implemented in a connection region and also makes it difficult to narrow the connection pitch.
An object of the present invention, for solving such a problem, is to provide a board connector capable of fine-pitch connection, with a highly reliable connection part against a drop impact and the like; and three-dimensional connecting structure using the board connector.